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WO1992006511A1 - Bloc de moteur monolithe piezoelectrique - Google Patents

Bloc de moteur monolithe piezoelectrique Download PDF

Info

Publication number
WO1992006511A1
WO1992006511A1 PCT/US1990/006535 US9006535W WO9206511A1 WO 1992006511 A1 WO1992006511 A1 WO 1992006511A1 US 9006535 W US9006535 W US 9006535W WO 9206511 A1 WO9206511 A1 WO 9206511A1
Authority
WO
WIPO (PCT)
Prior art keywords
disks
piezoelectric
thickness
solid state
stack
Prior art date
Application number
PCT/US1990/006535
Other languages
English (en)
Inventor
Chuong Q. Dam
Virgil R. Hester
Kurtis C. Kelley
Carey A. Towe
Original Assignee
Caterpillar Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Caterpillar Inc. filed Critical Caterpillar Inc.
Priority to EP90916897A priority Critical patent/EP0550435B1/fr
Priority to DE69028640T priority patent/DE69028640T2/de
Publication of WO1992006511A1 publication Critical patent/WO1992006511A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/871—Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H10N30/503—Piezoelectric or electrostrictive devices having a stacked or multilayer structure having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/872—Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/875—Further connection or lead arrangements, e.g. flexible wiring boards, terminal pins

Definitions

  • the field of the invention relates generally to solid state motor actuators. More particularly, the invention relates to a piezoelectric solid state motor stack structure. Still more particularly, the invention relates to a solid state motor stack structure having a wide operating temperature range.
  • electroexpansive materials have been employed in stacked structures for producing actuation used for fuel injection and valve control in diesel engines, for example.
  • Commercially manufactured solid state motor stacks, or actuators are produced using piezoelectric disks interleaved with metal foil electrodes.
  • Application of high voltage (e.g., 1000V DC) low current power to alternately biased electrodes causes each of the piezoelectric disks to expand or axially distort.
  • the additive deflection of the stacked disks is typically amplified by hydraulics to effectuate useful actuation.
  • the stacks are poled by application of a DC voltage and then encapsulated with a plastic insulative cover prior to final mounting within a transducer housing.
  • An example of a conventional low voltage multilayer piezoelectric ceramic actuator with varying thickness layers is taught by Takahashi et al. See Meeting on Ferroelectric Materials and Their Applications (5th), 1985. p. 206-208.
  • Takahashi et al. have developed a multilayer ceramic actuator used for impact matrix printer heads with an applied electric voltage of lower than 100V. Due to the low driving voltages, the Takahashi et al. multilayer actuators do not produce forces of large magnitude, and thus, the ceramic disks are prone to less failures.
  • Takahashi et al. have studied such actuators using finite element method analysis in an attempt to reduce stresses induced at an adhesive layer between the ceramic actuator and a mass load to which the body is attached.
  • the structure taught by Takahashi et al. includes two different thickness active layers and an inactive, non-stressing, layer disposed at one end of the multilayer actuator.
  • the mass load and ceramic layers have rectangular surface areas.
  • a surface of the mass load is attached to a surface of an inactive layer by an adhesive.
  • Adjacent the other surface of the inactive layer is a first active layer with a first thickness.
  • Stacked under the first active layer is a number of second active layers of a second thickness, the second thickness being smaller than the first thickness.
  • Two sets of electrodes are alternately interleaved with the active layers for application of the driving voltage.
  • the article reports that no mechanical rupture of the adhesive layer occurs as a result of such a structure. This result is further attributed to an edge hook on the mass load that overlaps down along a side edge of the inactive layer.
  • the present invention overcomes the deficiencies of the conventional technology noted above.
  • the present invention is directed to a piezoelectric solid state motor stack having a plurality of piezoelectric disks interleaved with a plurality of electrodes, with at least one first piezoelectric disk of a first thickness sandwiched between at least two second piezoelectric disks of a second thickness, the second thickness being different from the first thickness.
  • At least two electrodes are interleaved with at least two of the plurality of disks such that each electrode is in contact with a surface of at least one of the plurality of disks.
  • the sandwiched disks have surface facets partially covered with a conductive layer.
  • the invention may further include at least two disks of a third thickness, different from the first and second thicknesses, sandwiching between them the combination of the disks of the first and second thicknesses.
  • electrodes may be interleaved with the disks of the third thickness and the disks of the second thickness.
  • the invention may still further include at least two disks of a fourth thickness, different from the first through third thicknesses, sandwiching between them the combination of the disks of the first through third thicknesses. Still further electrodes are interleaved with the disks of the fourth thickness and the disks of the third thickness.
  • FIG. 1 is a cross-sectional view of a housed piezoelectric stack in connection with the present invention
  • FIG. 2 is an expanded view of a piezoelectric stack in connection with the present invention.
  • FIG. 3 is a sectional view of the disk/electrode stack of FIG. 2 with electrode tabs connected to respective busses and lead wires.
  • Piezoelectric solid state motor stacks according to the present invention are high-force devices that have minimized stack failure due to disk breakage caused by stress. Piezoelectric solid state motor stacks according to the present invention can be used to improve engine performance, reduce emissions, and reduce engine noise.
  • the utility of the present invention is not, however, limited to engine valve and fuel injector actuation.
  • the invention may be used in brake or shock absorbing systems, for example.
  • the invention may be used in a wide variety of devices or systems requiring fluid or mechanical actuation, as well as shock or sound wave production.
  • a particular advantage of the solid state motor stack of this invention is its ability to operate over a wide temperature range. Tests on prototype motor stacks have shown good results in operating environments of -40°C to 100°C.
  • FIG. 1 shows the j ezoelectric solid state stack motor 102 of the present invention in a housing 104.
  • the preferred embodiment for the housing and encapsulation of the present piezoelectric solid state stack motor invention is shown in the concurrently filed, commonly assigned co-pending application
  • the housing is a steel case and is cylindrical in shape with a hollow cylindrical cavity for housing the solid state stack. Threads 106 attach the piezoelectric solid state motor housing to an engine head. Plateau 108 represents a hexagonal cross section, if viewed from the top of FIG. 1. This hexagonal structure is not shown in the figure, but is used for tightening and loosening of the piezoelectric solid state motor housing on the engine head. Throughports are bored in the top end of the housing to permit bus lead wires 114 to exit the housing.
  • FIG. 2 is an expanded diagram of the disks forming the stack structure 200.
  • Ceramic disks suitable for use in making a motor stack are commercially available.
  • the piezoelectric solid state motor stack is bounded by non-polarized ceramic end caps 202.
  • the stack also includes thick ceramic disks 206, medium thick ceramic disks 208, inner thin ceramic disks 210, bus bars 212, 212', and lead wires 214, 214'.
  • each facet surface of the thick, medium thick and thin disks is coated with a conductive coating, preferably aluminum.
  • the application of the conductive layer may be accomplished by various methods as would become evident to those of skill in the art.
  • the conductive layer is preferably applied to all of the surface area of the upper and lower facets of the disks. Uniformity of the conductive layer is desired. However, uniformity and full facet surface coverage may be limited by the method used to apply the conductive layer.
  • the conductive layer may be applied by sputtering, spraying or mechanically rubbing atomic layers of the conductive material onto the facet surfaces of the disks. Chemical vapor deposition may also be used to apply the conductive layer.
  • the conductive layer may also comprise copper, nickel or silver. The conductive layer functions to more evenly spread the electric field across the surface of the disk when a voltage is applied to an adjacent electrode in the final stack structure.
  • the inner thin disks 210 are sandwiched by the medium thick disks 208. In a preferred embodiment, approximately 71 thin disks are used. The combination of the thin and medium thick disks are in turn sandwiched by the thick disks 206, and the combination of the thin, medium thick and thick disks are sandwiched by the end caps 202.
  • the thick, medium thick and thin disks have thicknesses of approximately 1.016, 0.762 and 0.508 mm, respectively.
  • the thickness of the end caps is preferably 2.500 mm.
  • Each of the first through fourth disk thicknesses has a tolerance of about + 0.013 mm.
  • FIG. 3 is a sectional view through line A-A in FIG. 2 showing the electrode assembly 300.
  • a top electrode 304 has a tab 316 electrically connected to a bus bar (wire) 312, for example, by soldering or laser welding.
  • a lead wire 314 is then electrically connected (again, by soldering or laser welding, for example) to the bus bar 312.
  • a next adjacent electrode (not shown) has a tab 318 offset from tab 316 (by about 180° in the example shown) .
  • Tab 318 is electrically connected to a second bus bar 312'.
  • the bus bar 312' in turn is electrically connected to a second lead wire 314'.
  • an assembly fixture comprir ng a half-cylindrical tube with a metal plug located ⁇ -- • _. the bottom, assembly begins by inserting a first end- cap ceramic disk into the assembly fixture. (Note that the facet surfaces of the end caps are not coated with a conductive layer.)
  • a first electrode is aligned in the assembly fixture on top of the first end cap ceramic disk.
  • the tab of the first electrode is given a first orientation.
  • the stacking of a thick disk is next, followed by another electrode. This next electrode is stacked on top of the thick disk and its tab is given a second orientation.
  • the second orientation is 180° from the first orientation.
  • the orientation, or circumferential displacement between successive electrode tabs, may vary as long as the
  • a medium thick disk is stacked on the second electrode.
  • a third electrode is stacked on top of the medium thick disk. The tab of the third electrode is oriented oppositely to that of the second stacked electrode and thus similarly to that of the first electrode.
  • a first thin disk is then stacked in the assembly fixture.
  • a fourth electrode again with an opposite orientation to the third stacked electrode, is then placed on the first thin disk. Successive thin disks are stacked with interleaved electrodes, such that every successive electrode is oriented oppositely to the immediately preceding electrode.
  • the disk/electrode stack comprises two longitudinal rows of disk tabs offset from each other by up to 180°.
  • each tab of each row of tabs is bent and presoldered to facilitate connection to a bus bar.
  • Each of the tabs is slotted so that the bus bar may be positioned in the slots.
  • the tab length as measured parallel to a line tangent to the circumference of the electrode, should be sufficient to permit free expansion and contraction of the stack during operation.
  • the electrode bus bar connection is accomplished as follows. Solder is applied to each of the tabs via a hand soldering gun, for example. The tabs may also be dipped in a solder bath. Two 22-gauge tin-copper wire bus bars are appropriately positioned along respective presoldered bent tab rows. The bus wires may be cleaned with isopropyl alcohol and treated with a liquid solder flux. Once positioned, the bus wires are soldered to the respective electrode tabs to form a bus structure.
  • Poling, or alignment of the thick, medium thick, and thin ceramic disks' dipoles is necessary to achieve axial expansion of the piezoelectric ceramic disks upon the application of an electrical potential to the stack. This is preferably done once the stack is assembled in accordance with guidelines provided by the ceramic manufacturer.
  • poling of the stack is accomplished at an elevated temperature (about 145°C) .
  • a poling voltage signal is applied to the stack in three stages. During the first stage a 0-volt to 1200-volt charge is applied linearly during a two-minute interval. For the second stage the voltage is held at 1200-volts for 10 minutes. Finally, the voltage is linearly reduced to 0-volts during a five-minute period.
  • the stack is then cooled to room temperature.
  • the ceramic end caps are not polarized during the poling process because they are not sandwiched by electrodes.
  • bus bars 212, 212' are soldered to the lead wires 214, 214, respectively, and a layer of shrink- wrap tubing is applied to the lead wires as an insulator.

Landscapes

  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

Bloc de moteur monolithe piézoélectrique (200) comprenant une pluralité de disques piézoélectriques (210, 208, 206, 202) intercalés avec une pluralité d'électrodes (204), dans lequel au moins un premier disque piézoélectrique (210) ayant une première épaisseur est disposé entre au moins deux seconds disques piézoélectriques (208) ayant une deuxième épaisseur qui diffère de la première épaisseur. Ladite structure comprend au moins deux électrodes (204) qui sont chacune intercalées avec au moins deux des disques de sorte que chaque électrode se trouve en contact avec une surface d'au moins un des disques. Les électrodes sont connectées à une source de potentiel électrique et polarisées par cette dernière pour produire un déplacement axial entre les surfaces d'extrémités opposées du bloc. En outre, le bloc peut comporter quatre épaisseurs de disques différentes, dans ce cas les disques les plus épais (202) prennent en sandwich par ordre décroissant les disques les plus minces (206, 208, 210) et les autres électrodes. La disposition et l'épaisseur des disques peuvent être symétriques par rapport à un axe central perpendiculaire à l'axe longitudinal du bloc.
PCT/US1990/006535 1990-09-28 1990-11-13 Bloc de moteur monolithe piezoelectrique WO1992006511A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP90916897A EP0550435B1 (fr) 1990-09-28 1990-11-13 Bloc de moteur monolithe piezoelectrique
DE69028640T DE69028640T2 (de) 1990-09-28 1990-11-13 Piezoelektrischer schichtachtiger festkörpermotor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58985590A 1990-09-28 1990-09-28
US589,855 1990-09-28

Publications (1)

Publication Number Publication Date
WO1992006511A1 true WO1992006511A1 (fr) 1992-04-16

Family

ID=24359835

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1990/006535 WO1992006511A1 (fr) 1990-09-28 1990-11-13 Bloc de moteur monolithe piezoelectrique

Country Status (4)

Country Link
EP (1) EP0550435B1 (fr)
AU (1) AU6719290A (fr)
DE (1) DE69028640T2 (fr)
WO (1) WO1992006511A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5367500A (en) * 1992-09-30 1994-11-22 The United States Of America As Represented By The Secretary Of The Navy Transducer structure
DE19620826A1 (de) * 1996-05-23 1997-11-27 Siemens Ag Piezoelektrisches Element sowie Verfahren zu dessen Herstellung
US5828160A (en) * 1994-11-25 1998-10-27 U.S. Philips Corporation Piezoelectric transducer
GB2375886A (en) * 2001-02-27 2002-11-27 Kyocera Corp Electrode connections for a laminated piezo-electric device
EP1160886A3 (fr) * 2000-05-31 2005-09-14 Denso Corporation Dispositif piézoélectrique pour un injecteur
US7042143B2 (en) * 2001-02-15 2006-05-09 Ceramtec Ag Innovative Ceramic Engineering Piezoceramic multilayer actuator with a transition region between the active region and the inactive head and foot regions
EP2126992B1 (fr) * 2007-01-23 2015-03-04 Epcos AG Composant piézoélectrique

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10025998A1 (de) * 2000-05-25 2001-12-06 Bosch Gmbh Robert Piezoaktor
DE102009000022A1 (de) * 2009-01-05 2010-07-08 Robert Bosch Gmbh Piezoelektrischer Stapelaktor
DE102011014447A1 (de) * 2011-03-18 2012-09-20 Epcos Ag Piezoaktor und Verfahren zur Kontaktierung eines Piezoaktors

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144655A1 (fr) * 1983-10-19 1985-06-19 Nec Corporation Transducteur électrostrictif comprenant des couches électrostrictives à épaisseur axiale variable

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3501099A (en) * 1967-09-27 1970-03-17 Physics Int Co Electromechanical actuator having an active element of electroexpansive material

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0144655A1 (fr) * 1983-10-19 1985-06-19 Nec Corporation Transducteur électrostrictif comprenant des couches électrostrictives à épaisseur axiale variable

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5367500A (en) * 1992-09-30 1994-11-22 The United States Of America As Represented By The Secretary Of The Navy Transducer structure
US5828160A (en) * 1994-11-25 1998-10-27 U.S. Philips Corporation Piezoelectric transducer
DE19620826A1 (de) * 1996-05-23 1997-11-27 Siemens Ag Piezoelektrisches Element sowie Verfahren zu dessen Herstellung
DE19620826C2 (de) * 1996-05-23 1998-07-09 Siemens Ag Piezoelektrischer Biegewandler sowie Verfahren zu dessen Herstellung
EP1160886A3 (fr) * 2000-05-31 2005-09-14 Denso Corporation Dispositif piézoélectrique pour un injecteur
US7042143B2 (en) * 2001-02-15 2006-05-09 Ceramtec Ag Innovative Ceramic Engineering Piezoceramic multilayer actuator with a transition region between the active region and the inactive head and foot regions
GB2375886A (en) * 2001-02-27 2002-11-27 Kyocera Corp Electrode connections for a laminated piezo-electric device
US6700306B2 (en) * 2001-02-27 2004-03-02 Kyocera Corporation Laminated piezo-electric device
GB2375886B (en) * 2001-02-27 2004-10-20 Kyocera Corp Laminated piezo-electric device
EP2126992B1 (fr) * 2007-01-23 2015-03-04 Epcos AG Composant piézoélectrique

Also Published As

Publication number Publication date
AU6719290A (en) 1992-04-28
DE69028640D1 (de) 1996-10-24
EP0550435B1 (fr) 1996-09-18
DE69028640T2 (de) 1997-04-30
EP0550435A1 (fr) 1993-07-14

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